Risk factors for early revision after total hip arthroplasty

Mid-term clinical outcomes of the uncemented Robert Mathys pressfit cup

BACKGROUND

The use of uncemented cups during total hip arthroplasty (THA) has gained popularity in recent years. The Robert Mathys (RM) pressfit cup, an uncemented monoblock implant is expected to preserve bone density due to its composition and external surface, while reducing backside wear with its monoblock construction. These factors should lead to a high survival rate of the implant.

AIM

To evaluate the mid-term survival and functional outcome of the RM Pressfit cup in a large study population.

METHODS

Between 2011 and 2020, we included 1324 patients receiving a primary THA using the RM pressfit cup. Final clinical follow-up was performed at 2 years postoperatively with the Dutch arthroplasty register used to assess implant status thereafter. Revision for acetabular failure and reason for revision were reported to evaluate implant survival, while the hip disability and osteoarthritis outcome score (HOOS) scores were used to assess functional outcome.

RESULTS

The mean age at surgery was 64.9 years. The mean follow-up was 4.6 years. Of the 1324 THAs performed, 13 needed cup revisions within 5 years after index THA: 5 due to aseptic loosening, 6 due to infection, 2 due to dislocation and 2 due to other causes. This resulted in a 5-year cup survival of 98.8% (95%CI: 98.1-99.5). Nine of the cup revisions occurred within the first year after index THA. HOOS scores increased significantly in all domains during the first year and levelled out during the second year.

CONCLUSION

In the present study, the RM pressfit cup demonstrated excellent clinical outcomes at mid-term follow-up; however, future studies are needed to assess the long-term outcomes of this acetabular implant.

Diagnostic value of procalcitonin in patients with periprosthetic joint infection: a diagnostic meta-analysis

Background

The success rate of periprosthetic joint infection (PJI) treatment is still low. Early diagnosis is the key to successful treatment. Therefore, it is necessary to find a biomarker with high sensitivity and specificity. The diagnostic value of serum procalcitonin (PCT) for PJI was systematically evaluated to provide the theoretical basis for clinical diagnosis and treatment in this study.

Methods

We searched the Web of Science, Embase, Cochrane Library, and PubMed for studies that evaluated the diagnostic value of serum PCT for PJI (from the inception of each database until September 2020). Two authors independently screened the literature according to the inclusion and exclusion criteria. The quality of each selected literature was evaluated by using the Quality Assessment of Diagnostic Accuracy Studies tool (QUADAS-2) tool. RevMan 5.3 software was used for the quality evaluation. The sensitivity, specificity, positive likelihood ratio (PLR), negative likelihood ratio (NLR), and diagnostic odds ratio (DOR) were merged by using Meta-DiSc 1.4 software. The area under the curve (AUC) and Q index were calculated after the summary receiver operating characteristic (SROC) was generated. We also performed subgroup analysis.

Results

A total of 621 patients were enrolled in the nine studies. The pooled sensitivity of serum PCT for PJI diagnosis was 0.441 [95% confidence interval (CI), 0.384-0.500], the pooled specificity was 0.852 (95% CI, 0.811-0.888), the pooled PLR was 2.271 (95% CI, 1.808-2.853), the pooled NLR was 0.713 (95% CI, 0.646-0.786), and the pooled DOR was 5.756 (95% CI, 3.673-9.026). The area under SROC (the pooled AUC) was 0.76 (0.72-0.79). Q index was 0.6948.

Conclusion

This study showed that PCT detection of PJI had poor diagnostic accuracy. Hence, the serum PCT is not suitable as a serum marker for PJI diagnosis.

Does Time to Aseptic Failure After Primary Total Hip Arthroplasty Affect Clinical and Patient-Reported Outcomes?

BACKGROUND

Evidence on the effects of time-to-failure from primary total hip arthroplasty (THA) to aseptic first-revision on clinical results and patient-reported outcome measures (PROMs) is scarce. Therefore, we sought to compare demographics, operative times, lengths of stay, discharge dispositions, 90-day readmissions, re-revision rates, mortalities, and PROMs between early and late aseptic THA revisions.

METHODS

This study is a retrospective review of a prospectively collected institutional database of all elective hip procedures. In total, 572 patients who underwent aseptic revision after primary THA from August 2015 to December 2018 were analyzed. Patients were stratified into either early revision (<3-years; n = 176) or late revision (≥3-years; n = 396) cohorts.

RESULTS

Significantly more patients were revised earlier for bone-related (ie, periprosthetic fractures) (22.7% versus 8.3%) or other various complications (19.9% versus 5.8%), whereas more late revisions were performed to treat implant-related failures (6.8% versus 37.1%), respectively. Operative time was significantly shorter in early versus late revisions (133 versus 157 minutes). A significantly higher delta-change/improvement from baseline/preoperative to 1-year postoperative was found for hip disability and osteoarthritis outcome score physical function (HOOS-PS), veterans-RAND-12 physical and mental components (VR-12-PCS and MCS, respectively) of early revisions. However, HOOS-PS and HOOS-Pain at 1-year of follow-up were significantly worse in early revisions.

CONCLUSION

With exception of operative time, time-to-failure had no significant influence on clinical results. Despite greater improvements on PROMs from preoperative to postoperative, patients undergoing early revisions after primary THA perceive significantly higher levels of pain and worse physical functionality at 1-year of follow-up.

Racial and Socioeconomic Disparities in Risk and Reason for Revision in Total Joint Arthroplasty

INTRODUCTION

Data regarding racial/ethnic and socioeconomic differences in revision total hip arthroplasty (rTHA) and revision total knee arthroplasty (rTKA) have been inconsistent. This study examined racial/ethnic and socioeconomic disparities in comorbidity-adjusted risk and reason for rTHA and rTKA.

METHODS

Patients who underwent rTHA or rTKA between 2006 and 2014 in the National Inpatient Sample were identified. Multivariable logistic regression models adjusted for payer status, hospital geographic setting, and patient characteristics (age, sex, and Elixhauser Comorbidity Index) were used to examine the effect of race/ethnicity and socioeconomic status on trends in annual risk of rTHA/rTKA and causes of rTHA/rTKA.

RESULTS

Black patients were less likely to undergo rTHA and more likely to undergo rTKA while Hispanic patients were more likely to undergo rTHA and less likely to undergo rTKA ( P < 0.001 for all) compared with White patients. Patients residing in areas of lower income quartiles were more likely to undergo rTHA and rTKA compared with those in the highest quartile ( P < 0.001), and these disparities persisted and widened over time. Black, Hispanic, and Asian patients were less likely to undergo rTHA/rTKA because of dislocation compared with White patients ( P < 0.001 for all). Patients from areas of lower income quartiles were more likely to undergo rTHA because of septic complications and less likely to require both rTHA and rTKA because of mechanical complications ( P < 0.001 for all).

DISCUSSION

Racial/ethnic and socioeconomic disparities exist in risk and cause of rTHA and rTKA. Increasing awareness and a focus on minimizing variability in hospital quality may help mitigate these disparities.

Cost-effectiveness of a novel, fluoroscopy-based robotic-assisted total hip arthroplasty system: A Markov analysis

BACKGROUND

The purpose of this study was to assess the cost-effectiveness of a novel, fluoroscopy-based robotic-assisted total hip arthroplasty (RA-THA) system compared to a manual unassisted technique (mTHA) up to 5 years post-operatively.

METHODS

A Markov model was constructed to compare the cost-effectiveness of RA-THA and mTHA. Cost-effectiveness was defined as an Incremental Cost-Effectiveness Ratio (ICER) <$50 000 or $100 000 per Quality Adjusted Life Year (QALY).

RESULTS

RA-THA patients experienced lower costs compared to mTHA patients at 1 year ($20 865.12 ± 9897.52 vs. $21 660.86 ± 9909.15; p < 0.001) and 5 years ($23 124.57 ± 10 045.48 vs. $25 756.42 ± 10 091.84; p < 0.001) post-operatively. RA-THA patients also accrued more QALYs (1-year: 0.901 ± 0.117 vs. 0.888 ± 0.114; p < 0.001; 5-years: 4.455 ± 0.563 vs. 4.384 ± 0.537 p < 0.001). Overall, RA-THA was cost-effective (1-year ICER: $-61 210.77; 5-year ICER: $-37 068.31).

CONCLUSIONS

The novel, fluoroscopy-based RA-THA system demonstrated cost-effectiveness when compared to manual unassisted THA.

Registry Data Show Complication Rates and Cost in Revision Hip Arthroplasty

INTRODUCTION

Revision THA (rTHA) places a burden on patients, surgeons, and health care systems because outcomes and costs are less predictable than primary THA. The purposes of this study were to define indications and treatments for rTHA, quantify risk for readmissions and evaluate the economic impacts of rTHA in a hospital system.

METHODS

The arthroplasty database of a hospital system was queried to generate a retrospective cohort of 793 rTHA procedures, performed on 518 patients, from 2017 to 2019 at 27 hospitals. Surgeons performed chart reviews to classify indication and revision procedure. Demographics, lengths of stay (LOS), discharge dispositions, and readmission data were collected. Analyses of direct costs were performed and categorized by revision type.

RESULTS

46.3% of patients presented for infection. Patients presenting for infection were 5.6 times more likely to have repeat rTHA than aseptic patients. Septic cases (4.3 days) had longer LOS than aseptic ones (2.4) (P < 0.0001). 31% of patients discharged to a skilled nursing facility (SNF). Direct costs were greatest for a two-stage exchange ($37,642), and lowest for liner revision ($8,979). Septic revisions ($17,696) cost more than aseptic revisions ($11,204) (P< 0.0001). The 90-day readmission rate was 21.8%. Septic revisions had more readmissions (13.5%) than aseptic revisions (8.3%).

CONCLUSIONS

Hip revisions, especially for infection, have an increased risk profile and create a major economic impact on hospital systems. Surgeons may use these data to counsel patients on risks of rTHA and advocate for improved reimbursement for the care of revision patients.

Developing Patient-Specific Statistical Reconstructions of Healthy Anatomical Structures to Improve Patient Outcomes

There are still numerous problems with modern joint replacement prostheses, which negatively influence patient health and recovery. For example, it is especially important to avoid failures and complications following hip arthroplasty because the loss of hip joint function is commonly associated with increased demand on the healthcare system, reoperation, loss of independence, physical disability, and death. The current study uses hip arthroplasty as a model system to present a new strategy of computationally generating patient-specific statistical reconstructions of complete healthy anatomical structures from computed tomography (CT) scans of damaged anatomical structures. The 3D model morphological data were evaluated from damaged femurs repaired with prosthetic devices and the respective damaged femurs that had been restored using statistical reconstruction. The results from all morphological measurements (i.e., maximum femoral length, Hausdorff distance, femoral neck anteversion, length of rotational center divergence, and angle of inclination) indicated that the values of femurs repaired with traditional prostheses did not fall within the +/-3 standard deviations of the respective patient-specific healthy anatomical structures. These results demonstrate that there are quantitative differences in the morphology of femurs repaired with traditional prostheses and the morphology of patient-specific statistical reconstructions. This approach of generating patient-specific statistical reconstructions of healthy anatomical structures might help to inform prosthetic designs so that new prostheses more closely resemble natural healthy morphology and preserve biomechanical function. Additionally, the patient-specific statistical reconstructions of healthy anatomical structures might be valuable for surgeons in that prosthetic devices could be selected and positioned to more accurately restore natural biomechanical function. All in all, this contribution establishes the novel approach of generating patient-specific statistical reconstructions of healthy anatomical structures from the CT scans of individuals' damaged anatomical structures to improve treatments and patient outcomes.

Causes of Early Hip Revision Vary by Age and Gender: Analysis of Data From a Statewide Quality Registry

BACKGROUND

While total hip arthroplasty (THA) is extremely successful, early failures do occur. The purpose of this study was to determine the cause of revision in specific patient demographic groups at 3 time points to potentially help decrease the revision risk.

METHODS

Data for cases performed between 2012 and 2018 from a statewide, quality improvement arthroplasty registry were used. The database included 79,205 THA cases and 1,433 revisions with identified etiology (1,584 in total). All revisions performed at <5 years from the primary THA were reviewed. Six groups, men/women, <65, 65-75, and >75 years, were compared at revision time points <6 months, <1 year, and <5 years.

RESULTS

There were obvious and significant differences between subgroups based on demographics and time points (P < .0001). Seven hundred and fifty-six (53%) of all revisions occurred within 6 months. The most common etiologies within 6 months (756 revisions) were fracture (316, 41.8%), dislocation/instability (194, 25.7%), and infection (98, 12.9%). At this early time point, the most common revision cause was fracture for all age/gender-stratified groups, ranging from 27.6% in young men to 60% in older women. Joint instability became the leading cause for revision after 1 year in all groups.

CONCLUSION

This quality improvement project demonstrated clinically meaningful differences in the reason for THA revision between gender, age, and time from surgery. Strategies based on these data should be employed by surgeons to minimize the factors that lead to revision.

The Utility of Machine Learning Algorithms for the Prediction of Early Revision Surgery After Primary Total Hip Arthroplasty

BACKGROUND

Revision total hip arthroplasty (THA) is associated with increased morbidity, mortality, and healthcare costs due to a technically more demanding surgical procedure when compared with primary THA. Therefore, a better understanding of risk factors for early revision THA is essential to develop strategies for mitigating the risk of patients undergoing early revision. This study aimed to develop and validate novel machine learning (ML) models for the prediction of early revision after primary THA.

METHODS

A total of 7,397 consecutive patients who underwent primary THA were evaluated, including 566 patients (6.6%) with confirmed early revision THA (<2 years from index THA). Electronic patient records were manually reviewed to identify patient demographics, implant characteristics, and surgical variables that may be associated with early revision THA. Six ML algorithms were developed to predict early revision THA, and these models were assessed by discrimination, calibration, and decision curve analysis.

RESULTS

The strongest predictors for early revision after primary THA were Charlson Comorbidity Index, body mass index >35 kg/m2, and depression. The six ML models all achieved excellent performance across discrimination (area under the curve >0.80), calibration, and decision curve analysis.

CONCLUSION

This study developed ML models for the prediction of early revision surgery for patients after primary THA. The study findings show excellent performance on discrimination, calibration, and decision curve analysis for all six candidate models, highlighting the potential of these models to assist in clinical practice patient-specific preoperative quantification of increased risk of early revision THA.

Medicaid Payer Status Is a Predictor of Early Postoperative Pain Following Upper Extremity Procedures

Background: The purpose of this study was to investigate the relationship between insurance status and patient-reported pain both before and after upper extremity surgical procedures. We hypothesized that patients with Medicaid payer status would report higher levels of pre- and postoperative pain and report less postoperative pain relief. Methods: In all, 376 patients who underwent upper extremity procedures by a single surgeon at an academic ambulatory surgery center were identified. Patient information, including insurance status and Visual Analog Scale pain score (VAS-pain) at baseline, 2 weeks, and 1, 3, and 6 months, were collected. VAS-pain scores were compared with t-tests and linear regression. Results: Preoperatively and at 2-week, 1-month, and 3-month follow-up, Medicaid patients reported statistically significant higher pain levels than patients with Private insurance, finding a mean adjusted increase of 0.51 preoperatively, 0.39 at 1 month, and 0.79 at 3 months. Preoperatively and at 3-month follow-up, Medicaid patients reported statistically significant higher pain than patients with Medicare, finding increases in VAS-pain of 0.99 preoperatively and 0.94 at 3 months. There was no difference in pain improvement between any insurance types at any time point (all P values > .05). Conclusions: Patients with Medicaid report higher levels of preoperative pain and early postoperative pain, but reported the same improvement in pain as patients with other types of insurance. As healthcare systems are becoming increasingly dependent on patient-reported outcomes, including pain, it is important to consider that differences may exist in subjective pain depending on insurance status.

Total Hip Arthroplasty After Hip Arthroscopy Has Increased Complications and Revision Risk

BACKGROUND

There has been an increase in hip arthroscopy (HA) over the last decade. After HA, some patients may ultimately require a total hip arthroplasty (THA). However, there is a scarcity of research investigating the outcomes in patients undergoing THA with a history of ipsilateral HA.

METHODS

The PearlDiver research program (www.pearldiverinc.com) was queried to capture all patients undergoing THA between 2015 and 2020. Propensity matching was performed to match patients undergoing THA with and without a history of ipsilateral THA. Rates of 30-day medical complications, 1-year surgical complications, and THA revision were compared using multivariate logistic regression. Kaplan-Meier analysis was conducted to estimate survival probabilities of each of the groups with patients undergoing THA .

RESULTS

After propensity matching, cohorts of 1940 patients undergoing THA without prior HA and 1940 patients undergoing a THA with prior HA were isolated for analysis. The mean time from HA to THA was 1127 days (standard deviation 858). Patients with a history of ipsilateral HA had an increased risk for dislocation (odds ratio [OR] 1.56, P = .03) and overall decreased implant survival within 4 years of undergoing THA (OR 1.53; P = .05). Furthermore, our data demonstrate the timing of previous HA to be associated with the risk of complications, as illustrated by the increased risk for dislocation (OR 1.75, P = .03), aseptic loosening (OR 2.18, P = .03), and revision surgery at 2 (OR 1.92, P = .02) and 4 years (OR 2.05, P = .01) in patients undergoing THA within 1 year of HA compared twitho patients undergoing THA more than 1 year after HA or with no previous history of HA.

CONCLUSION

Patients undergoing THA after HA are at an increased risk for surgical complications, as well as the need for revision surgery.

Association of Sex With Risk of 2-Year Revision Among Patients Undergoing Total Hip Arthroplasty

IMPORTANCE

The worldwide population is aging and includes more female individuals than male individuals, with higher rates of total hip arthroplasty (THA) among female individuals. Although research on this topic has been limited to date, several studies are currently under way.

OBJECTIVES

To evaluate the association between sex and 2-year revision after THA.

DESIGN, SETTING, AND PARTICIPANTS

This cohort study used data from statewide databases in New York and California between October 1, 2015, and December 31, 2018. Patients 18 years or older with osteoarthritis who underwent THA and had sex recorded in the database were included in the analysis.

EXPOSURE

Total hip arthroplasty.

MAIN OUTCOMES AND MEASURES

The outcome of interest was the difference in early, all-cause revision surgery rates after primary THA between women and men. The association of sex with the revision rate was examined using Cox proportional hazards regression analysis.

RESULTS

Of 132 826 patients included in the study, 74 002 (55.7%) were women; the mean (SD) age was 65.9 (11.0) years, and the median follow-up time was 1.3 years (range, 0.0-3.0 years). The 2-year revision rate was 2.5% (95% CI, 2.4%-2.6%) among women and 2.1% (95% CI, 2.0%-2.2%) among men. After adjusting for demographic characteristics, comorbidities, and facility volume, a minimal clinically meaningful difference was observed in revision rates despite women having a higher risk of all-cause revision compared with men (hazard ratio, 1.16; 95% CI, 1.07-1.26; P < .001). The risk of revision was increased among women compared with men in the subgroup of patients who were younger than 55 years (hazard ratio, 1.47; 95% CI, 1.20-1.81; P < .001).

CONCLUSIONS AND RELEVANCE

In this cohort study, no clinically meaningful difference in all-cause revision rates after primary THA was found between men and women at 2-year follow-up. The modest difference in the risk of revision between men and women in a small subgroup of patients younger than 55 years suggests that the risk of revision in this population should be studied further.

Medium term outcome of Lancaster cortical window technique for extraction of femoral stem in revision hip arthroplasty

Background

The extraction of a femoral stem during the revision hip arthroplasty can be a daunting task and can lead to catastrophic complications for the patient. A sound technique employed intraoperatively helps in the speedy recovery of the patient and reduces the risk of future surgical interventions. In this study, we present a medium-term outcome of our novel Lancaster cortical window technique which can be used for the removal of cemented or uncemented femoral stems.

Methods

The study was conducted at a specialist centre in the north-west of the UK from January 2014 to May 2019. This is a retrospective case series where patients were treated surgically using the Lancaster cortical window technique for removal of the femoral implant during a revision hip arthroplasty. Patient’s electronic notes and radiographs were used to evaluate the functional and radiological outcome.

Results

In this study, 18 patients were managed surgically using the novel Lancaster window technique. The mean age of all the patients was 81.5 years, and the male to female ratio was 10:8. Fifteen patients underwent revision surgery for aseptic loosening of the femoral and acetabular components. The rest of the three patients had revision surgery for a broken femoral stem, intraoperative femoral canal perforation while implanting a total hip replacement femoral stem and infection. Twelve femurs were replanted with uncemented long femoral stems and six with long cemented stems. The cortical window osteotomy united in all the patients in 4.2 months (mean). The mean follow-up of these patients is 20.9 months, and none of them had any implant subsidence or loosening at the time of their last follow-up.

Conclusion

We believe Lancaster cortical window technique can be safely used for the removal of cemented stems during revision hip arthroplasty without the need for expensive equipment.

Robotic Arm-assisted Total Hip Arthroplasty is More Cost-Effective Than Manual Total Hip Arthroplasty: A Markov Model Analysis

BACKGROUND

Total hip arthroplasty (THA) is the benchmark surgical treatment of advanced and symptomatic hip osteoarthritis. Preliminary evidence suggests that the robotic arm-assisted (RAA) technology yields more accurate and reproducible acetabular cup placement, which may improve survival rate and clinical results, but economic considerations are less well-defined. The purpose of this study was to compare the cost effectiveness of the RAA THA with manual THA (mTHA) modalities, considering direct medical costs and utilities from a payer's perspective.

METHODS

A Markov model was constructed to analyze two potential interventions for hip osteoarthritis and degenerative joint disorder: RAA THA and mTHA. Potential outcomes of THA were categorized into the transition states: infection, dislocation, no major complications, or revision. Cumulative costs and utilities were assessed using a cycle length of 1 year over a time horizon of 5 years.

RESULTS

RAA THA cohort was cost effective relative to mTHA cohort for cumulative Medicare and cumulative private payer insurance costs over the 5-year period. RAA THA cost saving had an average differential of $945 for Medicare and $1,810 for private insurance relative to mTHA while generating slightly more utility (0.04 quality-adjusted life year). The preferred treatment was sensitive to the utilities generated by successful RAA THA and mTHA. Microsimulations indicated that RAA THA was cost effective in 99.4% of cases.

CONCLUSIONS

In the Medicare and private payer scenarios, RAA THA is more cost effective than conventional mTHA when considering direct medical costs from a payer's perspective.

LEVEL OF EVIDENCE

Economic Level III. Computer simulation model (Markov model).

Analysis of early failure rate and its risk factor with 2157 total ankle replacements

The failure rate of TAA is still higher than that of other joint replacement procedures. This study aimed to calculate the early failure rate and identify associated patient factors. Data from the Korean Health Insurance Review and Assessment Service database from 2009 to 2017 were collected. We evaluated patients who had TAA as a primary surgical procedure. Early failure was defined as conversion to revision TAA or arthrodesis after primary TAA within five years. Patients with early failure after primary TAA were designated as the "Failure group". Patients without early failure and who were followed up unremarkably for at least five years after primary TAA were designated as the "No failure group". Overall, 2157 TAA participants were included. During the study period, 197 patients developed failure within five years postoperatively, for an overall failure rate of 9.1%. Significant risk factors for early failure were history of chronic pulmonary disease, diabetes, peripheral vascular disease, hyperlipidemia, dementia, and alcohol abuse. A significant increase of odds ratio was found in patients with a history of dementia, chronic pulmonary disease, and diabetes. Surgical indications and preoperative patient counseling should consider these factors.

Outcomes of outpatient total hip arthroplasty: a systematic review

INTRODUCTION

Similar to other total joint arthroplasty procedures, total hip arthroplasty (THA) is shifting to an outpatient setting. The purpose of this study was to analyse outcomes following outpatient THA.

METHODS

A comprehensive literature search was performed in April 2019 according to the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-analyses) guidelines using the PubMed, Embase, and Cochrane databases to identify articles that reported functional outcomes following outpatient total hip arthroplasty (THA).

RESULTS

9 articles, with 683 hips and a collective study period of 1988 to 2016, were included in this analysis. The mean age across all studies was 58.9 years and the follow-up period ranged from 4 weeks to 10 years. 4 studies reported Harris Hip Scores (HHSs) for their patient populations and in 3 studies, the average HHSs were excellent (>90) by 6 weeks postoperatively. The fourth study reported fair HHS scores for the outpatient and inpatient THA groups (75 ± 18, 75 ± 14, p = 0.77, respectively) at 4 weeks postoperatively. VAS scores improved significantly in two studies and NRS at rest and during activity improved significantly (p < 0.001) in a separate study. Overall, 88.1% of the enrolled patients were discharged the same day of surgery, as expected. Out of the 6 studies reporting on readmissions rate, there were two (0.34%) readmissions within 3 months of surgery.

CONCLUSION

In patients with no significant comorbidities, outpatient THA leads to favourable outcomes as well as low readmission rates in the short term.

Evidence-Based Hospital Procedural Volumes as Predictors of Outcomes After Revision Hip Arthroplasty

BACKGROUND

The aim of this study is to define the evidence-based institutional volume-outcome relationship in revision hip arthroplasty. We hypothesized that high-volume centers would be associated with superior outcomes, and that stratum-specific likelihood ratio (SSLR) analysis would delineate concrete volume thresholds for optimizing outcomes.

METHODS

The Nationwide Readmission Database was queried from 2011 to 2016 for patients undergoing revision hip arthroplasty. SSLR analysis was used to determine hospital volume cutoffs specific for outcomes of interest. Volume categories were confirmed with multivariate regression.

RESULTS

SSLR analysis produced distinct hospital volume cutoffs for all outcomes. Each subsequent volume threshold diminished patients' risk for adverse outcomes. Tertiles were identified for 90-day infection (≤6, 7-51, ≥52 cases per year). Quartiles were found for 90-day readmission (≤5, 6-15, 16-79, ≥80), 90-day prosthesis-related complication (≤5, 6-16, 17-65, ≥66), 90-day dislocation (≤5, 6-19, 20-79, ≥80), and non-home discharge (≤5, 6-15, 16-40, and ≥41). Quintiles were generated for extended length of stay >2 days (≤2, 3-10, 11-20, 21-30, ≥31). Heptiles were produced for medical complications within 90 days (≤2, 3-8, 9-16, 17-51, 52-89, ≥90).

CONCLUSION

This is the first known study to define evidence-based thresholds for the impact of hospital volume on revision joint arthroplasty. This supports the notion that institutional volume functions as a surrogate for protocolized interdisciplinary coordination of care and surgical experience, and that high-volume centers offer enhanced outcomes for complex cases. Additional studies should investigate the potential role for incentivization of such institutions, as they offer optimal outcomes for revision hip arthroplasty.

Impact of comorbidity on the short- and medium-term risk of revision in total hip and knee arthroplasty

Background

The impact of comorbidity on the risk of revision in patients undergoing Total Knee arthroplasty (TKA) and Total Hip Arthroplasty (THA) is not currently well known. The aim of this study was to analyze the impact of comorbidity on the risk of revision in TKA and THA.

Methods

Patients recorded in the Catalan Arthroplasty Register (RACat) between 01/01/2005 and 31/12/2016 undergoing TKA (n = 49,701) and THA (n = 17,923) caused by osteoarthritis were included. As main explanatory factors, comorbidity burden was assessed by the Elixhauser index, categorized, and specific comorbidities from the index were taken into account. Descriptive analyses for comorbidity burden and specific conditions were done. Additionally, incidence at 1 and 5 years’ follow-up was calculated, and adjusted Competing Risks models were fitted.

Results

A higher incidence of revision was observed when the number of comorbidities was high, both at 1 and 5 years for THA, but only at 1 year for TKA. Of the specific conditions, only obesity was related to the incidence of revision at 1 year in both joints, and at 5 years in TKA. The risk of revision was related to deficiency anemia and liver diseases in TKA, while in THA, it was related to peripheral vascular disorders, metastatic cancer and psychoses.

Conclusions

Different conditions, depending on the joint, might be related to higher revision rates. This information could be relevant for clinical decision-making, patient-specific information and improving the results of both TKA and THA.

The Association between High Body Mass Index and Early Clinical Outcomes in Patients with Proximal Femur Fractures

BACKGROUND

Fractures of the proximal femur constitute daily work in orthopedic trauma surgery. With the continuous increase of obesity in the general population, surgeons face several known technical challenges. The aim of this study was to investigate the association of high body mass index (BMI) in patients with proximal femur fractures with intra- and postoperative adverse events, as well as with functional outcomes after successful surgery.

METHODS

In this retrospective, single-center cohort study, 950 patients who sustained a fracture of the proximal femur (femoral neck fracture or trochanteric fracture) and underwent surgical treatment at our level I trauma center between 2003 and 2015 were included. Patient-specific data were obtained in regard to demographics, comorbidities, and fracture morphology. In-hospital postoperative complications (i.e., need for revision surgery, wound site infection, pneumonia, urinary tract infection, necessary transfusion, and deep-vein thrombosis) were analyzed, along with the length of hospitalization and overall mortality rate. Functional outcome was assessed using the Barthel index and the patient's ability to walk on crutches. Mortality rate and need for revision surgery were assessed over a two-year time period. Any adverse event was correlated to one of the four WHO's BMI groups.

RESULTS

The cohort included 80 (8.4%) underweight patients, 570 (60.0%) normal weight patients, 241 (25.4%) overweight patients, and 59 (6.2%) obese patients. We found more femoral neck fractures (506, or 53%) than trochanteric fractures (444, or 47%). In bivariate analysis, no significant difference was found in regard to overall mortality or postoperative complications. Hospitalization time (LOS) differed between the underweight (12.3 ± 4.8 days), normal (13.6 ± 7.8 days), overweight (14.2 ± 11.7 days), and obese patients (16.0 ± 9.7 days) (p = 0.040). Operation time increased stepwise with increasing BMI: underweight = 85.3 ± 42.9 min; normal weight = 90.2 ± 38.2 min; overweight = 99.9 ± 39.9 min; obese = 117.2 ± 61.5 min (p < 0.001). No significant difference was found by analyzing functional outcomes. However, patients with intermediate BMI levels (18.5-30 kg/m2) tended to achieve the best results, as represented by a higher Barthel index score and the patient's ability to walk on crutches.

CONCLUSION

Increased BMI in patients with proximal femur fractures is associated with both longer operation time and length of hospitalization (LOS). Postoperative mobilization and functional outcomes appear to follow a reversed J-curve distribution (with overweight patients showing the best functional results), whereas both obese and underweight patients have associated poorer function.

[there any association of metabolic disturbances with joint destruction and pain?]

Osteoarthritis and type 2 diabetes mellitus represent two the most common chronic diseases. They possess many shared epidemiologic traits, have common risk factors, and embody heterogeneous multifactorial pathologies, which develop due to interaction of genetic an environmental factors. In addition, these diseases are often occurring in the same patient. In spite of the differences in clinical manifestation both diseases have similar disturbances of cellular metabolism, primarily associated with ATP production and utilization. The review discusses molecular mechanisms determining pathophysiological processes associated with glucose and lipid metabolism as well as the means aiming to alleviate the disturbances of energy metabolism as a new a therapeutic approach.

Risk factors for readmission within thirty days following revision total hip arthroplasty

BACKGROUND

The number of total hip arthroplasties (THA) being performed has been steadily increasing for decades. With increased primary THA surgical volume, revision THA numbers are also increasing at a steady pace. With the aging, increasingly comorbid patient populations and newly imposed financial penalties for hospitals with high readmission rates, refining understanding of factors influencing readmission following THA is a research priority. We hypothesize that numerous preoperative medical comorbidities and postoperative medical complications will emerge as significant positive risk factors for 30-day readmission.

METHODS

ACS-NSQIP database identified patients who underwent revision THA from 2005 to 2015. The primary outcome assessed was hospital readmission within 30 days. Patient demographics, preoperative comorbidities, laboratory studies, operative characteristics, and postsurgical complications were compared between readmitted and non-readmitted patients. Logistic regression identified significant independent risk factors for 30-day readmission among these variables.

RESULTS

10,032 patients underwent revision THA in the ACS-NSQIP from 2005 to 2015; 855 (8.5%) were readmitted within 30-days. Increasing age, the presence of preoperative comorbidities, high ASA class, and increased operative time were significant positively associated independent risk factors for 30-day readmission. Several postoperative medical and surgical complications such as myocardial infarction, stroke, pneumonia, and sepsis demonstrated significant positive associations with readmission.

CONCLUSION

Identifying and understanding risk factors associated with readmission allows for the implementation of evidence-based interventions aimed at minimizing risk and reducing 30-day readmission rates following revision THA.

Effect of hospital volume on outcomes of total hip arthroplasty: a systematic review and meta-analysis

BACKGROUND

A shift in the healthcare system towards the centralization of common yet costly surgeries, such as total hip arthroplasty (THA), to high-volume centers of excellence, is an attempt to control the economic burden while simultaneously enhancing patient outcomes. The "volume-outcome" relationship suggests that hospitals performing more treatment of a given type exhibit better outcomes than hospitals performing fewer. This theory has surfaced as an important factor in determining patient outcomes following THA. We performed a systematic review with meta-analyses to review the available evidence on the impact of hospital volume on outcomes of THA.

MATERIALS AND METHODS

We conducted a review of PubMed (MEDLINE), OVID MEDLINE, Google Scholar, and Cochrane library of studies reporting the impact of hospital volume on THA. The studies were evaluated as per the inclusion and exclusion criteria. A total of 44 studies were included in the review. We accessed pooled data using random-effect meta-analysis.

RESULTS

Results of the meta-analyses show that low-volume hospitals were associated with a higher rate of surgical site infections (1.25 [1.01, 1.55]), longer length of stay (RR, 0.83[0.48-1.18]), increased cost of surgery (3.44, [2.57, 4.30]), 90-day complications (RR, 1.80[1.50-2.17]) and 30-day (RR, 2.33[1.27-4.28]), 90-day (RR, 1.26[1.05-1.51]), and 1-year mortality rates (RR, 2.26[1.32-3.88]) when compared to high-volume hospitals following THA. Except for two prospective studies, all were retrospective observational studies.

CONCLUSIONS

These findings demonstrate superior outcomes following THA in high-volume hospitals. Together with the reduced cost of the surgical procedure, fewer complications may contribute to saving considerable opportunity costs annually. However, a need to define objective volume-thresholds with stronger evidence would be required.

TRIAL REGISTRATION

PROSPERO CRD42019123776.

Higher Rate of Early Revision Following Primary Total Knee Arthroplasty in Patients Under Age 55: A Cautionary Tale

BACKGROUND

There has been an increased number of total knee arthroplasties (TKAs) performed in young and active patients. Although improved materials have decreased the likelihood of early catastrophic wear, concerns remain with the performance and survivorship of TKA implants in this patient population. The purpose this study is to evaluate perioperative complications, patient-reported outcomes, and implant survivorship of TKAs performed in patients under age 55.

METHODS

We retrospectively reviewed 4259 primary TKAs performed over a 4-year period. There were 741 TKAs in patients under age 55. The primary outcome of interest was rate of revision at 30 days, 1, 2, and 5-year time points. Secondary outcomes included postoperative transfusion rate, length of stay, rate of deep vein thrombosis/pulmonary embolism, need for manipulation under anesthesia, readmission and reoperation within 30 days, as well as patient-reported outcomes.

RESULTS

There were 3518 patients over 55 years and 741 patients under 55 years. Overall, 175 patients required revision (4.1%). Patients under 55 years had significantly higher cumulative revision rate at 1 (3.4% vs 1.8%, P < .001), 2 (5.0% vs 2.4%, P < .001), and 5 years (7.3% vs 3.7%, P < .001). Patients under 55 years had a higher rate of early reoperation. Patients over 55 years required more transfusions and suffered a higher rate of early deep vein thrombosis. Patients over 55 years had significantly greater improvements in Patient Reported Outcome Measurement Information System Global 10 Physical scores at 6 months postoperatively compared to patients under 55 years.

CONCLUSIONS

Despite improvements in TKA implants, young and active patients remained at higher risk of early revision compared to older patients. The data should be used to counsel young prospective TKA patients about the early risk of reoperation and non-wear-related complications.

Risk factors for early revision after total hip and knee arthroplasty: National observational study from a surgeon and population perspective

Aims

To identify predictors of early revision (within 3 years of the index operation) for hip and knee replacement (HR, KR) from both surgeon and population perspectives.

Patients and methods

Hierarchical logistic regression on national administrative data for England for index procedures between April 2009 and March 2014.

Results

There were 315,273 index HR procedures and 374,530 index KR procedures for analysis. Three-year revision rates were 2.1% for HR and 2.2% for KR. The highest odds ratios for HR were for 3+ previous emergency admissions, drug abuse, Parkinson’s disease, resurfacing and ages under 60; for KR these were patellofemoral or partial joint replacement, 3+ previous emergency admissions, paralysis and ages under 60. Smaller effects were found for other comorbidities such as obesity (HR) and diabetes (KR). From a population perspective, the only population attributable fractions over 5% were for male gender, uncemented total hip replacements and partial knee or patellofemoral replacements.

Conclusions

Meeting the rising demand for revision surgery is a challenge for healthcare leaders and policymakers. Our findings suggest optimising patients pre-operatively and improving patient selection for primary arthroplasty may reduce the burden of early revision of arthroplasty. Our study gives useful information on the additional risks of various comorbidities and procedures, which enables a more informed consent process.

Clinical relevance

Surgeons should make patients with certain risk factors such as age and procedure type aware of their higher revision risk as part of shared decision-making.

An international comparison of THA patients, implants, techniques, and survivorship in Sweden, Australia, and the United States

Background and purpose - International comparisons of total hip arthroplasty (THA) practices and outcomes provide an opportunity to enhance the quality of care worldwide. We compared THA patients, implants, techniques, and survivorship in Sweden, Australia, and the United States. Patients and methods - Primary THAs due to osteoarthritis were identified using Swedish (n = 159,695), Australian (n = 279,693), and US registries (n = 69,641) (2003-2015). We compared patients, practices, and implant usage across the countries using descriptive statistics. We evaluated time to all-cause revision using Kaplan-Meier survival curves. We assessed differences in countries' THA survival using chi-square tests of survival probabilities. Results - Sweden had fewer comorbidities than the United States and Australia. Cement fixation was used predominantly in Sweden and cementless in the United States and Australia. The direct anterior approach was used more frequently in the United States and Australia. Smaller head sizes (≤ 32 mm vs. ≥ 36 mm) were used more often in Sweden than the United States and Australia. Metal-on-highly cross-linked polyethylene was used more frequently in the United States and Australia than in Sweden. Sweden's 5- (97.8%) and 10-year THA survival (95.8%) was higher than the United States' (5-year: 97.0%; 10-year: 95.2%) and Australia (5-year: 96.3%; 10-year: 93.5%). Interpretation - Patient characteristics, surgical techniques, and implants differed across the 3 countries, emphasizing the need to adjust for demographics, surgical techniques, and implants and the need for global standardized definitions to compare THA survivorship internationally.

Primary Hip and Knee Arthroplasty in a Safety Net Hospital: Substance Abuse and Other Factors Affecting Short-term Complications

BACKGROUND

Arthroplasty outcomes and patient risk factors have not been studied in detail in safety net hospital settings. This study examines the relationship between selected risk factors and short-term complications in such a population, including a large subgroup with treated substance abuse.

METHODS

This retrospective cohort study contains 486 consecutive patients after primary hip and knee arthroplasty. One hundred three of these had a history of substance abuse and completed a 1-year sobriety pathway preoperatively. Primary outcomes included the presence of any complication, deep infection, and reoperation. Bivariable analyses were used to compare outcomes with demographic and health risk factors. A multivariate analysis was performed to identify independent risk factors.

RESULTS

Adverse outcomes were more common in patients with higher rates of substance abuse, mental illness, and infection with human immunodeficiency virus (HIV) and hepatitis C virus (HCV). Substance abuse alone was not an independent risk factor for the occurrence of complications, but infections with HIV and HCV were. In the substance abuse subgroup, with its higher prevalence of risk factors, complications were more frequent (31.1% vs 16.4%, P = .0009), and, in particular, deep infections (5.8% vs 1.8%, P = .0256).

CONCLUSIONS

Specific risk factors were associated with short-term complications in safety net arthroplasty patients. Despite having completed a preoperative sobriety pathway, substance abuse patients had more complications than did others. However, substance abuse alone was not an independent risk factor for adverse surgical outcomes. Other factors, notably HCV and HIV infection that were more common in patients with substance abuse, were most closely associated with adverse outcomes.

Can patient-reported outcomes predict re-operations after total hip replacement?

PURPOSE

We investigated if patient-reported outcomes (PROMs) one year after total hip replacement (THR) can predict the risk of re-operation using data from the Swedish Hip Arthroplasty Register.

METHODS

A total of 75,899 patients with THR due to osteoarthritis operated in 2002-2014 were included. We used Kaplan-Meier and Cox regression to investigate the relationship between one-year post-operative PROMs and risk of re-operation (all types of further hip surgery). The predictive power of the model and post-operative PROMs were evaluated by concordance index (C).

RESULTS

Kaplan-Meier estimates for not being re-operated at eight years was 95.5% (95%CI; 95.3-95.8). Cox regression analyses showed that all PROMs, except for EQ-VAS, were associated with re-operation. The full model had a concordance index of 0.68. Satisfaction (C = 0.65) and pain (C = 0.65) in isolation had the highest predictive power.

CONCLUSIONS

Worse PROMs predicted higher risk of re-operation. Therefore, we believe PROMs may be helpful in identifying patients at risk for re-operation and timely address their problems.

National Incidence of Patient Safety Indicators in the Total Hip Arthroplasty Population

BACKGROUND

The Centers for Medicare & Medicaid Services use the incidence of patient safety indicators (PSIs) to determine health care value and hospital reimbursement. The national incidence of PSI has not been quantified in the total hip arthroplasty (THA) population, and it is unknown if patient insurance status is associated with PSI incidence after THA.

METHODS

All patients in the Nationwide Inpatient Sample (NIS) who underwent THA in 2013 were identified using the International Classification of Diseases, Ninth Revision, Clinical Modification codes. The incidence of PSI was determined using the International Classification of Diseases, Ninth Revision, diagnosis code algorithms published by the Centers for Medicare & Medicaid Services and the Agency for Healthcare Research and Quality. The association of insurance status and the incidence of PSI during the inpatient episode was determined by comparing privately insured and Medicare patients with Medicaid/self-pay patients using a logistic regression model that controlled for patient demographics, patient comorbidities, and hospital characteristics.

RESULTS

In 2013, the NIS included 68,644 hospitalizations with primary THA performed during the inpatient episode. During this period, 429 surgically relevant PSI were recorded in the NIS. The estimated national incidence rate of PSI after primary THA was 0.63%. In our secondary analysis, the privately insured cohort had significantly lower odds of experiencing one or more PSIs relative to the Medicaid/self-pay cohort (odds ratio, 0.47; 95% confidence interval, 0.29-0.76).

CONCLUSION

The national incidence of PSI among THA patients is relatively low. However, primary insurance status is associated with the incidence of one or more PSIs after THA. As value-based payment becomes more widely adopted in the United States, quality benchmarks and penalty thresholds need to account for these differences in risk-adjustment models to promote and maintain access to care in the underinsured population.

Relationship between GNAS1 T393C polymorphism and aseptic loosening after total hip arthroplasty

BACKGROUND

Aseptic loosening is a main cause for revision surgery after total hip arthroplasty (THA) and there is no reliable marker for the early detection of patients at high risk. This study has been performed to validate association of the T393C polymorphism (rs7121) in the GNAS1 gene, encoding for the alpha-subunit of heterotrimeric G-protein Gs, with risk for and time to aseptic loosening after THA, which has been demonstrated in our previous study.

METHODS

231 patients with primary THA and 234 patients suffering from aseptic loosening were genotyped for dependency on GNAS1 genotypes and analyzed.

RESULTS

Genotyping revealed almost similar minor allele frequencies of 0.49 and 0.46, respectively. Consistently, genotype distributions of both groups were not significantly different (p = 0.572). Neither gender nor GNAS1 genotype showed a statistically significant association with time to loosening (p = 0.501 and p = 0.840). Stratification by gender, as performed in our previous study, was not able to show a significant genotype-dependent difference in time (female p = 0.313; male p = 0.584) as well as median time to aseptic loosening (female p = 0.353; male p = 0.868).

CONCLUSION

This study was not able to confirm the results of our preliminary study. An association of the GNAS1 T393C polymorphisms with risk for and time to aseptic loosening after THA is unlikely.

Relative impact of hospital and surgeon procedure volumes on primary total hip arthroplasty revision: a nationwide cohort study in France

BACKGROUND

Both surgeon and hospital procedure volumes have been found to be associated with total hip arthroplasty (THA) outcomes. However, little research has been conducted on the relative influence. We studied the association between THA survivorship and both hospital and surgeon procedure volumes, considering their relative impact.

METHODS

A population-based cohort included all patients aged ≥40 years having received a unilateral primary THA from 2010 to 2011, from the French National Health Insurance Database. Patients were followed up until the end of 2014. The outcome was THA revision. Exposures of interest were procedure volumes, divided into tertiles: <1.5, 1.5-4, >4 and <7, 7-15, >15 procedures per month defined as low, medium, and high volumes for surgeon and hospital, respectively.

RESULTS

The cohort had 62,906 patients, with mean age 69 years and women 57%. Mean surgeon and hospital volumes were 8 and 23 procedures per month, respectively, and 5%, 72%, 22% and 7%, 28%, 65% of THAs were implanted by a low-, medium-, and high-volume surgeon or in a low-, medium-, and high-volume hospital, respectively. Median follow-up was 45 months (range, 0-57 months). In multivariate analysis, adjusted for both surgeon and hospital volumes, for patient and THA characteristics, a lower surgeon volume was associated with poorer THA survivorship (adjusted hazard ratio [aHR] = 1.19; 95% confidence interval [CI], 1.07-1.34 and aHR = 1.70; 95% CI, 1.40-2.05, for medium- and low-volume surgeon, respectively, compared with that of high volume), whereas hospital volume was not.

CONCLUSIONS

This study brings evidence to support the notion that THAs performed by high-volume surgeons in French private hospitals have higher survivorship in the first 4 years.

Social Context and Value-Based Care: A Capabilities Approach for Addressing Health Disparities

Racial disparities in health are persistent and pervasive in the United States. Researchers and policymakers have known for decades that access to health care is not sufficient for addressing health disparities because of the socially situated roots of the disparities. We argue that the lack of progress in alleviating health disparities is the result of a lack of overarching framework to guide both policymakers and researchers in their efforts. We propose Amartya Sen's capabilities approach as a theoretical framework that is expansive enough to address both the social context in which health occurs as well as the quality of health care provided. In this article, we use a subset of veterans receiving care from the Veterans Health Administration to review the theoretical concepts that link social inequalities with health disparities. Next, we provide empirical evidence of disparities in health based on race within the Veterans Health Administration, and we then provide a theoretical explanation for those disparities that exist at a system level. We close with a detailed examination of the applicability of the capabilities approach in addressing health disparities in the United States.

Dual-Mobility Articulations for Patients at High Risk for Dislocation

BACKGROUND

The purpose of this study was to evaluate the performance of dual-mobility articulations in patients at high risk for dislocation after revision total hip arthroplasty.

METHODS

We reviewed the results of 36 consecutive revision total hip arthroplasties performed on patients considered high risk for instability. Indications for inclusion included abductor insufficiency, recurrent instability, failure of constrained liner, or inadequate intraoperative stability when trialing.

RESULTS

At a minimum of 2 years, there were 4 (11.1%) repeat revisions including both dual-mobility liners that were cemented into an acetabular shell and 2 for deep infection treated with a 2-stage exchange. There was one dislocation that was successfully closed reduced but no revisions for recurrent instability. The mean Harris hip score improved from 45 to 90 points (P < .001).

CONCLUSION

Dual-mobility articulations are associated with a low rate of failure with no revisions for instability in this challenging group of patients.

Late complications and long-term outcomes following aseptic revision of a hip arthroplasty performed for oncological resection

PURPOSE

In order to achieve an oncological margin during limb salvage surgery for tumours around the hip, part or the entire hip joint is frequently sacrificed. Hip arthroplasty restores a functional extremity and achieves limb salvage. Currently there is a paucity of data concerning the late complications, long-term survival, and the risks of re-revision following aseptic revision of a total hip arthroplasty (THA) performed following an oncological resection.

METHODS

We identified 78 patients who underwent aseptic revision of a THA which was performed for an oncological process involving the hip from 1972 to 2006. All patients had a minimum 5 years of follow-up with a mean of 13 years. Outcomes were compared to 1,378 patients undergoing aseptic revision of a THA that was performed for a diagnosis of osteoarthritis.

RESULTS

The mean 5-, 10-, 15-, and 20-year re-revision-free survival for an oncologic process of the hip was 100%, 85%, 69%, and 57%. Within this cohort, younger patients were at an increased risk of revision surgery. There was no difference in survivorship of the revision implant at any of the aforementioned time points between the oncologic and osteoarthritis cohorts. Patients with an oncologic diagnosis had a higher rate of dislocations, component wear, and loosening compared to the osteoarthritis group.

CONCLUSION

Late complications following revision surgery of THA performed for an oncologic resection are common. The results of this study provide information for counselling patients on implant survivorship and complications following aseptic revision THA after index surgery for an oncologic indication.

The Effect of Diabetes Mellitus on Total Joint Arthroplasty Outcomes

Diabetes has negative effects on the outcomes of total joint arthroplasty, including increased numbers of complications, decreased function, early revision, and higher costs. The prevalence of diabetes is increasing rapidly worldwide; therefore, the orthopaedic surgeon should have an understanding of how diabetes affects surgical outcomes.

Insulin Dependence Increases the Risk of Failure After Total Knee Arthroplasty in Morbidly Obese Patients

The aims of this study were to compare the outcomes between nondiabetic (n=1284), type II diabetic (n=530), and insulin-dependent type II diabetic (n=164) morbidly obese (body mass index ≥40 kg/m(2)) patients undergoing primary total knee arthroplasty at 6-year follow-up. Patients with type II diabetes mellitus (DM) had similar outcomes when compared with non-DM patients. However, patients with insulin dependence had an increased risk of reoperation (hazard ratio [HR], 1.8; P=.005), revision (HR, 2; P=.02), and periprosthetic joint infection (HR, 2.1; P=.03), as well as decreased 10-year implant survivorship (84% vs 92%; P=.01) when compared to non-DM patients. Prospective studies should further evaluate outcomes and optimization measures within this population.

LEVEL OF EVIDENCE

Level III-prognostic study.

Short-term Risk of Revision THA in the Medicare Population Has Not Improved With Time

INTRODUCTION

Advances in surgical technique, implant design, and clinical care pathways have resulted in higher expectations for improved clinical outcomes after primary THA; however, despite these advances, it is unclear whether the risk of revision THA actually has decreased with time. Understanding trends in short- and mid-term risks of revision will be helpful in directing clinical, research, and policy efforts to improve THA outcomes.

QUESTION/PURPOSES

We therefore asked (1) whether there have been changes in overall short- and mid-term risks of revision THA among patients in the Medicare population who underwent primary THA between 1998 and 2010; and (2) whether there are different demographic factors associated with short- and mid- term risks of revision THA.

METHODS

Using the Medicare 5% national sample database, patients who underwent primary THA between 1998 and 2010 followed by subsequent revision through 2011 were identified by ICD-9-CM procedure codes 81.51 and 81.53/80.05/00.70-00.73, respectively. This dataset included a random sample of Medicare beneficiaries based on their social security number. Only patients with minimum 1-year followup after primary THA were included in our analysis. A total of 64,260 patients who underwent primary THA were identified from the 1998 to 2010 Medicare 5% dataset. Eighty-eight percent of the patients had 1-year followup providing a final study cohort of 56,700 patients. The risk of revision was evaluated at 1, 3, 5, and 7 years. Multivariate Cox regression was used to evaluate temporal trends in revision risk using two methods to account for time effects with periods 1998 to 2002, 2003 to 2007, and 2008 to 2010 for the index year of primary THA, and individual year of index of primary THA as independent variables. The analysis adjusted for patient age, sex, race, census region, Charlson score, and socioeconomic status.

RESULTS

The 7-year crude risk of revision THA declined from 7.10% in 1998 to 2002 to 6.09% in 2008 to 2010, representing a 14.4% overall reduction in adjusted risk of revision (p = 0.0058; 95% CI, 4.4%-23%). Similarly, the 5-year crude risk of revision THA declined from 5.96% in 1998 to 2002 to 5.11% in 2008 to 2010, representing a 14.2% overall reduction in adjusted risk of revision (p = 0.0069; 95% CI, 4.1%-23%). However, the adjusted risk of revision THA at 3 years was not different from 1998 to 2002 (4.70%) and 2008 to 2010 (4.03%; p = 0.1176). Similarly, the adjusted risk of revision at 1 year did not differ from 1998 to 2002 (2.83%) and 2008 to 2010 (2.42%; p = 0.3386). Patients with more comorbidities had a greater adjusted risk of revision (p < 0.001) at all times: 94% (95% CI, 58%-138%) and 56% (95% CI, 33%-84%) at 1 year and 7 years, respectively, for Charlson score of 5+ vs 0).

CONCLUSIONS

Although the mid-term (5 and 7 years) risk of revision THA has decreased during the past 14 years among Medicare beneficiaries who underwent primary THA, the short-term risk has not. These findings suggest that greater clinical, research, and policy emphasis is needed to identify potentially avoidable causes of early failure after primary THA in patients in the Medicare population, and multistakeholder solutions are needed to optimize short-term outcomes.

LEVEL OF EVIDENCE

Level III, therapeutic study.

Comparing co-morbidities in total joint arthroplasty patients using the RxRisk-V, Elixhauser, and Charlson Measures: a cross-sectional evaluation

BACKGROUND

Joint arthroplasty patients have a high prevalence of co-morbidities and this impacts their surgical outcomes. There are different ways to ascertain co-morbidities and appropriate measurement is necessary. The purpose of this study was to: (1) describe the prevalence of co-morbidities in a cohort of total hip arthroplasty (THA) and knee arthroplasty (TKA) patients using two diagnoses-based measures (Charlson and Elixhauser) and one prescription-based measure (RxRisk-V); (2) compare the agreement of co-morbidities amongst the measures.

METHODS

A cross-sectional study of Australian veterans undergoing THAs (n = 11,848) and TKAs (n = 18,972) between 2001 and 2012 was conducted. Seventeen co-morbidities were identified using the Charlson, 30 using the Elixhauser, and 42 using the RxRisk-V measure. Agreement between co-morbidities was calculated using Kappa (κ) statistics.

RESULTS

Combining measures, 64 conditions were identified, of these 28 were only identified using the RxRisk-V, 11 using the Elixhauser, and 2 using the Charlson. The most prevalent conditions was pain treated with anti-inflammatories (58.7% THAs, 55.9% TKAs), pain treated with narcotics (55.0% THAs, 50.9% TKAs), hypertension (56.0% THAs and TKAs), and anticoagulation disorders (53.0% THAs, 48.6% TKAs). Diabetes was the only condition with substantial agreement (all κ > 0.6) amongst all measures. When comparing the diagnoses based algorithms, agreement was high for overlapping conditions (all κ > 0.71).

CONCLUSIONS

Different measures identified different co-morbidities, provided different estimates for the same co-morbidity, and had different levels of agreement for common co-morbidities. This highlights the importance of understanding co-morbidity measures and using them appropriately in studies and case-mix adjustments analyses.

Using Medications for Prediction of Revision after Total Joint Arthroplasty

This study evaluated the ability of a pharmacy based co-morbidity measure (RxRisk-V) to predict odds of one and five years revision in total hip arthroplasty (THA) and total knee arthroplasty (TKA) and compared its performance to the more commonly used co-morbidity measures in orthopaedics (Charlson and Elixhauser). 11,848 patients with THAs and 18,972 with TKAs performed between 2001 and 2012 were evaluated. Using a combination of conditions, identified by both the pharmacy and diagnoses based coding algorithms, models with acceptable predictive ability of THA and TKA revision were developed. These findings suggest prescription based co-morbidity measures can positively contribute to case-mix adjustment and outcome prediction in this patient population.

Patient Selection in Short Stay Total Hip Arthroplasty for Medicare Patients

There is a trend towards shortening inpatient hospital stays following total hip arthroplasty (THA) in an effort to reduce healthcare costs and potentially decrease complications. The purpose of this study was to identify patients who are at risk for readmission, complications, and mortality after short stay THA. The Medicare sample (1997-2011) was used to identify THA patients with 1-2-day (Group A, n=2949) or 3-day (Group B, n=8707) stays. Complication risks were similar between groups, though there was a reduced risk for hospitalization for Group A (adjusted hazard ratio=0.90, P=0.029). These findings suggest that age and comorbidities, particularly diabetes and cardiovascular conditions, have the greatest effect on readmission and event risk after short stay THA.

When and how do prosthetic hips fail after total hip arthroplasties?-A retrospective study

BACKGROUND/PURPOSE

Understanding failure modes, time to revision, and vulnerable components in revision hips could help reduce the risk of revision surgeries. Our aim was to investigate the association between the index diagnosis and the failure mode in patients undergoing revision surgeries.

METHODS

A total of 402 patients who underwent a first revision surgery in a single hospital between 2000 and 2012 were recruited in a retrospective study. Multiple logistic regression analysis was used to evaluate the association of the index diagnosis of the primary total hip arthroplasty and short-term failure, as well as specific failure mode that occurred early, while controlling for sex, age, and the type of prosthesis.

RESULTS

The mean time to revision due to all failure modes was 9.48 (standard deviation = 6.08) years. Defining short-term failure as a time to revision <5 years after total hip arthroplasty, the primary failure mode was infection (32.4%), followed by loosening (25.7%) and instability (17.1%). In multivariate analysis, as compared to osteonecrosis, patients with index diagnosis as infection was significantly associated with revision due to infection (odds ratio = 9.69, p = 0.013). In addition, osteoarthritis increased the odds of loosening (odds ratio = 4.18, p = 0.012). In contrast to studies in the United States and Europe, acetabular component revisions were the most common type found in our study.

CONCLUSION

This study demonstrates that, compared with patients with osteonecrosis, patients with infection and osteoarthritis had higher odds of revision due to infection and loosening, respectively. Further studies are needed to examine the cause-effect relationship between index diagnosis and mode of failure.

Morbid Obesity: Increased Risk of Failure After Aseptic Revision TKA

BACKGROUND

Patients with obesity are known to have a higher risk of complications after primary TKA; however, there is a paucity of data regarding the effects of obesity with revision TKAs.

QUESTIONS/PURPOSES

We asked the following questions : (1) Are patients with morbid obesity (BMI≥40 kg/m2) at greater risk for repeat revision, reoperation, or periprosthetic joint infection (PJI) compared with patients without obesity (BMI<30 kg/m2) after an index revision TKA performed for aseptic reasons? (2) Do patients who are not obese achieve higher Knee Society pain and function scores after revision TKA for aseptic reasons?

METHODS

We used a retrospective cohort study with 1:1 matching for sex, age (±3 years) and date of surgery (±1 year) to compare patients with morbid obesity with patients without obesity with respect to repeat revision, reoperation, and PJI. Using our institution's total joint registry, we identified 1291 index both-component (femoral and tibial) aseptic revision TKAs performed during a 15-year period (1992-2007). Of these, 120 revisions were in patients with morbid obesity (BMI≥40 kg/m2) and 624 were in patients with a BMI less than 30 kg/m2. We then considered only patients with a minimum 5-year followup, which was available for 77% of patients with morbid obesity and 76% of patients with a BMI less than 30 kg/m2 (p=0.84). All patients with morbid obesity who met criteria were included (morbid obesity group: n=93; average followup, 7.9 years) and compared with a matched cohort of patients with a BMI less than 30 kg/m2 (nonmorbid obesity group: n=93; average followup, 7.3 years). Medical records were reviewed to gather details regarding complications and clinical outcomes.

RESULTS

Overall, patients with morbid obesity had an increased risk of repeat revision (hazard ratio [HR], 3.8; 95% CI, 1.2-16.5; p<0.02), reoperation (HR, 2.9; 95% CI, 1.3-7.4; p<0.02), and PJI (HR, 6.4; 95% CI, 1.2-119.7; p<0.03). Implant survival rates were 96% (95% CI, 92%-100%) and 100% at 5 years, and 81% (95% CI, 70%-92%) and 93% (95% CI, 86%-100%) at 10 years for the patients with morbid obesity and those without morbid obesity, respectively (p=0.02). At 10 years, The Knee Society pain (90 [95% CI, 88-92] vs 76 [95% CI, 71-81]; p<0.01) and function (61 [95% CI, 53-69] vs 57 [95% CI, 42-52]; p<0.01) scores were higher in patients with a BMI less than 30 kg/m2 compared with patients with morbid obesity.

CONCLUSION

Morbid obesity is associated with increased rates of rerevision, reoperation, and PJI after aseptic revision TKA. As the time-sensitive nature of revision surgery may not always allow for patient or comorbidity optimization, these results emphasize the need for improving our care of patients with morbid obesity earlier on during the osteoarthritic process. Additional studies are needed to risk stratify patients in the morbidly obese population to better guide patient selection and effective optimization.

LEVEL OF EVIDENCE

Level III, therapeutic study.

Risk for Complication after Total Joint Arthroplasty at a Center of Excellence: The Impact of Patient Travel Distance

Healthcare reorganization and bundled payment schemes have resulted in increased patient travel distances in orthopedics. Travel distance has been previously associated with increased complication risk but has yet to be studied in orthopedics. We analyzed the impact of patient travel distance on short-term complications. We reviewed 38,887 TJAs performed between 2008 and 2011 and identified 1606 complications in 1110 procedures. There was no significant association between complication risk and patient travel distance. Complication risk was associated with age, ASA class, Medicare and Medicaid status (P<0.0001 for all). Regional centers of excellence appear to be a viable model in healthcare reorganization however continued attention should be paid to attenuating the individual patient factors associated with complication at these institutions.

The adverse effects of diabetes on osteoarthritis: update on clinical evidence and molecular mechanisms

Projected increases in the prevalence of both diabetes mellitus (DM) and osteoarthritis (OA) ensure their common co-existence. In an era of increasing attention to personalized medicine, understanding the influence of common comorbidities such as DM should result in improved care of patients with OA. In this narrative review, we summarize the literature addressing the interactions between DM and OA spanning the years from 1962 to 2014. We separated studies depending on whether they investigated clinical populations, animal models, or cells and tissues. The clinical literature addressing the influence of DM on OA and its therapeutic outcomes suggests that DM may augment the development and severity of OA and that DM increases risks associated with joint replacement surgery. The few high quality studies using animal models also support an adverse effect of DM on OA. We review strengths and weaknesses of the common rodent models of DM. The heterogeneous literature derived from studies of articular cells and tissues also supports the existence of biochemical and biomechanical changes in articular tissues in DM, and begins to characterize molecular mechanisms activated in diabetic-like environs which may contribute to OA. Increasing evidence from the clinic and the laboratory supports an adverse effect of DM on the development, severity, and therapeutic outcomes for OA. To understand the mechanisms through which DM contributes to OA, further studies are clearly necessary. Future studies of DM-influenced mechanisms may shed light on general mechanisms of OA pathogenesis and result in more specific and effective therapies for all OA patients.